In an electronic apparatus, such as a communication device, a bandpass filter that passes electric signals of only specific frequencies is used. In particular, a bandpass filter is widely used, which forms a passband including an even-mode resonance frequency and an odd-mode resonance frequency by using even mode resonance and odd mode resonance in a resonance system in which two resonators having the same resonance frequency are electromagnetically coupled to each other. In this bandpass filter, a difference between the even-mode resonance frequency and the odd-mode resonance frequency varies depending on the strength of electromagnetic coupling between the two resonators. The passband width of the bandpass filter is thus determined (see, e.g., Patent Literature (PTL) 1).